Contamination by microorganisms is one of the most troublesome problems encountered today and there is often a need to sterilize devices such as medical instruments and the like.
In U.S. Pat. Nos. 4,169,123 and 4,169,124 methods are disclosed of cold gas sterilization using hydrogen peroxide gas of temperatures below 80.degree. C. The liquid hydrogen peroxide is volatilized and the hydrogen peroxide vapor is then introduced into the sterilization chamber by air displacement.
U.S. Pat. No. 4,642,165 discloses a method of vaporizing successive increments of a multicomponent liquid such as an aqueous solution of hydrogen peroxide, for injection into a vacuum chamber. The vacuum in the chamber draws the multicomponent vapor into the chamber.
U.S. Pat. No. 4,512,951 discloses a method of liquid contact hydrogen peroxide sterilization. Goods to be sterilized are maintained in the sterilization chamber at a temperature below the dew point of the vapor sterilant. An aqueous solution of hydrogen peroxide is vaporized and passed into the evacuated sterilization chamber where, upon contact with the goods, the vapor condenses to form a liquid layer of sterilant on the goods. The vacuum in the chamber draws the vapor inside the chamber.
United Kingdom Patent No. 1,582,060 discloses a similar liquid contact hydrogen peroxide sterilization method operated without a vacuum chamber. Liquid hydrogen peroxide is pumped through an ultrasonic spray nozzle which is operated by a stream of dehydrated air. A mist of hydrogen peroxide is sprayed into a container and mixed with hot air to change the mist into a vapor. The vapor is piped into a nonpressurized sterilization chamber where it condenses on a cool moving web of material. A stream of hot air in an adjacent chamber removes the hydrogen peroxide layer from the web. The stream is then passed to a water separator where it is relieved of the sterilant.
In some other prior art systems, when the object such as a medical instrument has been sterilized, it must be removed from the sterilization chamber and handled in some form to be prepared for and transported to the medical facility for use. For instance, with the use of endoscopes which have multiple hollow tubes therein for air, water, vacuum and the like, the endoscope is placed in a container and input and output fluid connections are made to the appropriate endoscope connections and the chamber is sealed. A sterilizing fluid is introduced into the chamber where it not only surrounds and bathes the endoscope with the sterilizing agent, but is also passed through all of the hollow tubes of the endoscope by applying a vacuum on the other port, thus sterilizing the interior of any tubes.
However, the endoscope may still have moisture on it and the ambient air may then enter the chamber after the sterilization process or the endoscope may simply be removed from the chamber and placed in ambient air so that it will dry before use.
Such a system is inherently dangerous since any handling of the endoscope after sterilization or exposing it to ambient air after sterilization provides opportunity for recontamination of the endoscope. Further, it may continue to have moisture on the interior thereof which may contain contaminants that could be injected into the next patient with whom the endoscope is to be used.
These disadvantages of the prior art are overcome by the present invention which includes a sealable cassette in which the endoscope or other medical device is placed. The cassette has first and second fluid sealing ports for the introduction and removal of a sterilizing fluid. The endoscope or other medical instrument, if hollow, is coupled to the output port. The cassette is formed of two identical halves which are placed in superimposed sealable relationship with each other to form a hollow chamber. A latch is placed on one or more handles on the cassette to create a presealing condition to allow a vacuum to be introduced at the outlet port.
The cassette is then placed in an outer oven-like container or warming chamber where the temperature is properly maintained. Connections are made through the input and output ports on the cassette such that the sterilizing agent may be introduced through a first port to bathe the outside of the medical instrument or other object, such as an endoscope, while one end of the hollow object, such as the endoscope, is coupled to the output port where a vacuum is supplied external to the cassette to pull the sterilization agent inside the cassette through the interior passageways of the endoscope. When the sterilization process is completed, the warming chamber is opened and the sterilizing cassette is simply removed from the chamber with the input and output ports being uncoupled from their respective sources. A tight seal is maintained and the object remains in the sterilized interior of the cassette until the cassette is opened or the device is to be used. It can be stored, transported and handled without adversely affecting the sterilization of the object therein.
The cassette may have one or more handles for carrying it and a latch is utilized on at least one of the handles to preload the seals between the two cassette halves to enable a vacuum to be applied to the cassette when it is placed in the outer warming chamber. In the preferred-embodiment, one latch has a generally C-shaped portion having an arcuate section extending above, from the back of and curved toward the front of the C to form a handle for the latch. A projection on each end of the C generally faces each other and the projections are sufficiently spaced apart to engage a corresponding one of the handle portions to hold the handle portions of the cassette in a locked relationship with respect to each other. In one embodiment of the cassette that utilizes the C-shaped latch, a sloped shoulder is formed on each of the first and second handle portions such that the shoulders converge in a direction away from the cassette chamber. A trough or depression is formed on each cassette handle portion adjacent the highest portion of each slope such that as the C-shape body portion is pivoted from one handle portion toward the other, the projection on the upper outer end of the C-shape body portion engages and moves up the corresponding sloped shoulder of the handle and forces the sloped shoulders toward one another to seal the cassette. The upper outer end projection of the C engages the corresponding trough and locks the cassette halves together.
In the second embodiment, the latch is integrally formed and pivotally attached to the first handle portion. It has a generally horizontal leg for lifting the latch and a vertical leg with a projection thereon for latching contact with the second handle portion. A spring tab extends at an angle from the junction of the horizontal and vertical legs for releasably engaging the first handle portion. It releasably holds the vertical leg projection in positive latching contact with the second handle portion and flexes when the horizontal leg is lifted to release the latching contact of the vertical leg projection with the second handle portion to enable the cassette halves to be separated. In such case the respective handle portion in each cassette half includes an orifice in opposing relationship with the orifice in the opposing handle. A lip portion is formed in each of the first and second orifices. A horizontal projection at the bottom of the vertical leg provides latching engagement with the lip portion of the orifice in the second handle portion. The spring tab abuts the lip portion of the orifice in the first handle portion to provide a force to the vertical leg to hold the latch in positive latching contact with the lip portion in the orifice in the second handle portion. The spring tab is cantilevered and integrally formed with the horizontal and vertical legs of the catch. Thus by lifting up on the horizontal portion of the leg, the cantilevered spring tab is bent towards the vertical leg, thus allowing the vertical leg to move out of latching contact with the second handle portion and can be moved upwardly out of the orifice in both the first and second handle portions to allow the cassette halves to be separated.
Thus, it is an object of the present invention to provide a system for sterilizing a device and in particular a device such as a medical object as, for instance, an endoscope.
It is also an object of the present invention to provide a sealable cassette or container having a chamber in which the device to be sterilized can be placed, the chamber sealed, the cassette placed in an environmental control container, the device sterilized and the cassette removed from the container (where the proper temperature is maintained) and is kept in the sterilized condition inside the cassette until the next use of the device is required. No handling of the device to be sterilized is required after the device is placed in the cassette.
It is still another object of the present invention to provide a latch for the cassettes to maintain the cassettes in a sealable state to allow depressurization of the cassette for sterilization of the object therein and for maintaining the sealed relationship after the sterilization process is completed to prevent the object therein from being recontaminated.
It is still another object of the present invention to provide a sterility guard to indicate the possibility of a container having been opened if the guard has been removed.